PURPOSE: In this project, we will use a combination of computational and experimental techniques to characterize MYC dynamics in a variety of cell systems and in response to a range of important biological stimuli. We will use a range of quantitative approaches (single cell imaging of MYC protein expression, genome-wide analysis of MYC binding, high throughput transcriptomic analysis, etc) to idnetify systems-level properties of MYC regulation and function. From these approaches, we aim to identify novel strategies for manipulating MYC activity in disease contexts, especially cancers in which MYC is deregulated. MATERIALS AND METHODS: To measure the dynamics of MYC expression, we will primarily use long-term time-lapse fluorescence microscopy of living individual cells in which MYC has been fluorescently tagged. We will use chemical and genetic perturbations to alter MYC dynamics and determine the effects on cellular functions. We will use a suite of high-throughput sequencing technologies to quantify MYC binding and activity. Using computational modeling, we will integrate these data with measurements of cellular outcomes to predict pathway behavior in response to specific perturbations. PROGRESS IN FY2017: In this year, we focused on the regulation and function of MYC suppression during the cellular response to DNA damage. We identified the tumor suppressor p53 as a key factor in MYC repression in this stress response. We identified a p53 binding site distal to the MYC gene as a key site for MYC repression, and found that p53 is required for DNA-damage dependent chromatin rearrangements at the MYC promoter that lead to MYC repression. Using a system to perturb MYC expression, we showed that the normal repression of MYC during the DNA damage response is important for suppressing general transcription, while at the same time p53-dependent activation of stress response genes can bypass the general transcriptional inhibition. As a result of this global inhibition with specific activation mechanism of transcriptional control, cell cycle arrest is maintained and programmed cell death is suppressed. Our findings from this study were accepted for publication in Molecular Cell.